package com.thread.countDownLatch;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.concurrent.CountDownLatch;

//一个同步辅助类，在完成一组正在其他线程中执行的操作之前，它允许一个或多个线程一直等待。
public class CountDownLatchDemo {

	final static SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    public static void main(String[] args) throws InterruptedException {
    	//构造方法参数指定了计数的次数
        CountDownLatch latch=new CountDownLatch(2);//两个工人的协作
        Worker worker1=new Worker("zhang san", 5000, latch);
        Worker worker2=new Worker("li si", 8000, latch);
        worker1.start();//
        worker2.start();//
        //调用此方法会一直阻塞当前线程，直到计时器的值为0
        latch.await();//等待所有工人完成工作
        System.out.println("all work done at "+sdf.format(new Date()));
    }


    static class Worker extends Thread{
        String workerName;
        int workTime;
        CountDownLatch latch;
        public Worker(String workerName ,int workTime ,CountDownLatch latch){
             this.workerName=workerName;
             this.workTime=workTime;
             this.latch=latch;
        }
        public void run(){
            System.out.println("Worker "+workerName+" do work begin at "+sdf.format(new Date()));
            doWork();//工作了
            System.out.println("Worker "+workerName+" do work complete at "+sdf.format(new Date()));
            //当前线程调用此方法，则计数减一
            latch.countDown();//工人完成工作，计数器减一

        }

        private void doWork(){
            try {
                Thread.sleep(workTime);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

}
